Semiconductor device and production method therefor

ABSTRACT

An object of the invention is to provide a method for producing a conductive member having low electrical resistance, and the conductive member is obtained using a low-cost stable conductive material composition that does not contain an adhesive. A method for producing a semiconductor device in which silver or silver oxide provided on a surface of a base and silver or silver oxide provided on a surface of a semiconductor element are bonded, includes the steps of arranging a semiconductor element on a base such that silver or silver oxide provided on a surface of the semiconductor element is in contact with silver or silver oxide provided on a surface of the base, temporarily bonding the semiconductor element and the base by applying a pressure or an ultrasonic vibration to the semiconductor element or the base, and permanently bonding the semiconductor element and the base by applying heat having a temperature of 150 to 900° C. to the semiconductor device and the base.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending application Ser. No.12/691,947 filed on Jan. 22, 2010, which claims priority under 35 U.S.C.§119(a) to Patent Application No. 2009-013713 filed in Japan on Jan. 23,2009. The entire contents of each of these applications are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a productionmethod therefor, especially, a method for bonding a semiconductorelement (hereinafter sometimes referred to as a “die-attach method”).

2. Description of Related Art

Various bonding methods for mounting semiconductor elements such astransistors, ICs, and LSIs have been known. In addition, various bondingmethods that are suitable with, among semiconductor elements, lightemitting semiconductor elements such as light emitting diodes(hereinafter sometimes referred to as “LEDs”) and laser diodes(hereinafter sometimes referred to as “LDs”) have been know as well.

Conventionally, die-attach methods for semiconductor elements areroughly classified into two categories, i.e., bonding methods that useepoxy resin adhesives (hereinafter referred to as “resin bonding”) andbonding methods that use eutectic metals having an eutectic point at ahigh temperature of 300° C. or greater (hereinafter referred to as“eutectic bonding”) (see, for example, Patent Documents 1 and 2). Suchdie-attach methods are selected according to the similarity between thethermal expansion behaviors of a lead frame material and a substratematerial on which a semiconductor element is to be mounted, as well asthe reliability, cost, and like factors. For example, resin bonding isused for light emitting diodes for use in liquid-crystal back lights ofsmall portable devices and like devices whose cost is given priority,and eutectic bonding is generally used for light emitting diodes forlighting purposes that are required to last a long time and for laserdiodes that are required to be highly reliable.

A resin for use in resin bonding is mostly a thermosetting resin such asan epoxy resin. A paste in which a powder of a conductive material suchas silver is dispersed is also a type of resin for resin bonding. Inresin bonding, a liquid epoxy resin is heated to 150 to 200° C. forcuring. Resin bonding is convenient in that curing can be readilyaccomplished at low temperatures of 150 to 200° C. In particular,thermal degradation of the thermosetting resin and melting of thethermoplastic resin can be avoided in a general-purpose surface-mountedsemiconductor device in which a lead frame is molded in advance.

However, the heat generation due to the recent increase of light energyattained by light emitting diodes, laser diodes and like devices as wellas the recent increase in input electricity, causes the resin itselfthat is used in resin bonding to deteriorate with time, resulting inproblems such as discoloration and deterioration of the bondingstrength. The glass transition temperature, which is an indicator interms of temperature of the modulus of elasticity of a resin, is,because curing is performed at a low temperature, lower than the soldermounting temperature applied when a semiconductor device is mounted asan electronic component, and thus separation resulting fromdeterioration of the resin strength caused by thermal shock duringsolder mounting is likely to occur. Moreover, resin bonding that usesonly an epoxy resin and resin bonding that uses a silver paste both havea problem in that, since they have poor thermal conductivity andinsufficient heat releasability, light emitting diodes and the likebecome unilluminable.

On the other hand, eutectic bonding that uses an alloy of gold and tincan solve the aforementioned problems of resin bonding.

However, eutectic bonding requires heating to 300° C. or greater whenbonding, and is therefore not applicable to widely used resin packagesof PPA (polyphthalamide) or the like since such packages cannotwithstand high temperatures. In addition, even if silver plating, whichhas high reflectivity, is provided over the surface of a wiring board ora lead frame on which a light emitting diode is to be mounted, lightextraction effect cannot be enhanced since eutectic metals have poorreflectivity.

-   Patent Document 1: JP 2004-128330 A-   Patent Document 1: JP 2006-237141 A

SUMMARY OF THE INVENTION

Therefore, with the foregoing in mind, it is an object of the presentinvention to provide a method for mounting a reliable semiconductorelement and to provide a method for mounting a semiconductor elementthat has high heat releasability. Accordingly, a low-cost semiconductordevice and a simple production method of a semiconductor device can beprovided.

The present invention relates to a method for producing a semiconductordevice in which silver or silver oxide provided on a surface of a baseand silver or silver oxide provided on a surface of a semiconductorelement are bonded, and the method includes the steps of arranging thesemiconductor element on the base such that silver or silver oxideprovided on a surface of the semiconductor element is in contact withsilver or silver oxide provided on a surface of the base, temporarilybonding the semiconductor element and the base by applying a pressure oran ultrasonic vibration to the semiconductor element or the base, andpermanently bonding the semiconductor element and the base by applyingheat having a temperature of 150 to 900° C. to the semiconductor deviceand the base. It is thus possible to provide a method for producing areliable semiconductor device since components that are likely todeteriorate are not used. Moreover, since the semiconductor element andthe base are directly bonded, the thermal conductivity is high and theheat generated by the semiconductor element can be efficientlytransferred to the base. Furthermore, the semiconductor element can bemounted without special equipment, so a simple production method for asemiconductor device can be provided.

The temperature for the permanent bonding is preferably in a range of150 to 400° C., and more preferably in a range of 150 to 320° C. This isbecause the bonding can be attained at relatively low temperatures.Moreover, this is because at those temperatures the semiconductorelement is not destroyed, and the package in which the semiconductorelement is mounted and the mounted base do not undergo thermaldeformation.

It is preferable to simultaneously perform the step of temporarilybonding and the step of permanently bonding. This is because thesemiconductor element can be mounted in a simpler manner.

The step of permanently bonding is performed preferably in air or in anoxygen atmosphere, thereby enabling the fusion reaction of silver to befurther enhanced.

The present invention relates to a semiconductor device having a dieshear strength of 13 to 55 MPa in which silver or silver oxide providedon a surface of a base and silver or silver oxide provided on a surfaceof a semiconductor element are directly bonded. While a resin adhesive,a silver paste, a eutectic metal, or the like is present between thebase and the semiconductor element in conventional bonding such as resinbonding and eutectic bonding, the base and the semiconductor element aredirectly bonded in the present invention. A eutectic component that usesan alloy of gold and tin or a component such as an epoxy resin or asilver paste is not present between the semiconductor element and thebase, and it is thus possible to provide a reliable semiconductordevice. In particular, a semiconductor device that has a high die shearstrength and that is unlikely to undergo separation can be provided.

A light emitting semiconductor element may be used for the semiconductorelement. The light emitting semiconductor element and the base aredirectly bonded, and it is thus possible to provide a semiconductordevice that does not undergo photodegradation. The present invention isapplicable also to transistors, ICs, LSIs, capacitors, Zener diodes, andthe like other than light emitting semiconductor elements such as lightemitting diodes and laser diodes.

The semiconductor element used may include a semiconductor layerdisposed on a translucent inorganic substrate; the translucent inorganicsubstrate is provided with first silver on the side opposite thesemiconductor layer and furnished with a buffering member bonded withthe first silver; and the silver or silver oxide is provided on asurface of the buffering member. It is thus possible to enhance theefficiency of extracting light from the semiconductor device. Moreover,the separation at the interface of the translucent inorganic substrateand the first silver can be reduced, thereby enhancing the die shearstrength.

By adopting the above-described configuration, a low-cost reliablesemiconductor device that does not include components that undergodeterioration and a production method therefor can be provided.Moreover, since the semiconductor element and the base can be directlybonded, a semiconductor device with high heat releasability can beprovided. Furthermore, a simple production method for a semiconductordevice can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional drawing showing the semiconductorlight emitting element of the first embodiment when mounted.

FIG. 2 is a schematic cross-sectional drawing showing the semiconductorlight emitting element of the second embodiment when mounted.

FIG. 3 is a schematic cross-sectional drawing showing the semiconductorlight emitting element of the third embodiment when mounted.

DETAILED DESCRIPTION OF THE INVENTION

The inventors found that when a composition containing silver particleshaving an average particle diameter of 0.1 to 15 μm is sintered in thepresence of a metal oxide or in an oxygen or ozone environment or inair, which serves as an oxidizer, silver particles are fused even at atemperature, for example, near 150° C. and a conductive material can beobtained. In contrast, when a composition containing silver particleshaving an average particle diameter of 0.1 to 15 μm is sintered in anitrogen environment, no conductive material was obtained at a lowtemperature near 150° C. Based on these findings, the inventorsaccomplished a method for producing a conductive material that includesthe step of sintering a composition containing silver particles havingan average particle diameter of 0.1 to 15 μm in the presence of a metaloxide or in an oxygen or ozone environment or in air that serves as anoxidizer.

Furthermore, the inventors, during the process of investigating themechanism of the present invention in detail, performed low-temperaturebonding of smoothed silver-sputtered surfaces in the presence of oxygento examine the bondability of silver surfaces that are not organicallycontaminated, and found that, even if silver particles are not used,sufficient bonding can be attained by temporarily bonding by applying apressure or an ultrasonic vibration to the surfaces to be bonded andthen carrying out low-temperature heating. The inventors applied thisfinding to develop a highly reliable semiconductor device and havearrived at the present invention. The inventors found at the same timethat it is useful also as a method for providing a low-costsemiconductor device.

In the die-attach method of the present invention, the mechanism of bondformation is not clear, but it can be presumed to be as follows. Whensilver-coated surfaces formed by silver sputtering, silver vapordeposition, silver plating, or a like technique are brought into contactin an oxygen or ozone environment or in air that serves as an oxidizer,some portions of the silver-coated surfaces are locally oxidized, andthe silver oxide formed by the oxidation exchanges oxygen in acatalyst-like manner at the places of contact on the silver coatedsurfaces, and through repetitive redox reactions, bonds are formed.Moreover, it is also presumed that bonds are formed through the samemechanism also in an inert gas atmosphere by forming silver oxide inadvance by oxidizing the silver-coated surfaces. Bonds are presumablyformed through such a mechanism, and it is therefore possible to providea highly reliable low-cost semiconductor device when a semiconductordevice is produced according to the die-attach method of the presentinvention.

The present invention relates to a method for producing a semiconductordevice in which silver or silver oxide provided on a surface of a baseand silver or silver oxide provided on a surface of a semiconductorelement are bonded, and the method includes the steps of arranging thesemiconductor element on the base such that silver or silver oxideprovided on a surface of the semiconductor element is in contact withsilver or silver oxide provided on a surface of the base, temporarilybonding the semiconductor element and the base by applying a pressure oran ultrasonic vibration to the semiconductor element or the base, andpermanently bonding the semiconductor element and the base by applyingheat having a temperature of 150 to 900° C. to the semiconductor deviceand the base. The temperature applied to the semiconductor element andthe base is preferably 150 to 400° C., and particularly preferably 150to 320° C. The production method of the present invention can imparthigh emission efficiency to a semiconductor device that uses a lightemitting semiconductor element such as a light emitting diode and alaser diode. Since no bonding material is interposed, low electricalresistance and low thermal resistance are attained, and it is thuspossible to provide enhanced reliability. Moreover, since bonding can beperformed in the same temperature range as in resin bonding, thermaldeterioration of the plastics components used in the semiconductordevice can be avoided. Since no resin is used in the bonding components,the life of the semiconductor device is extended. Furthermore, since theproduction process is simple and the amount of noble metal used isextremely low, a semiconductor device can be produced inexpensively.

An organic or inorganic substrate furnished with a lead frame ormetallic wiring can be used as the base, and the surface of the leadframe or the surface of the metal wiring is coated with silver. A silveroxide surface can be attained by oxidizing the entire base or a part ofthe base on which a semiconductor element is to be mounted. Irrespectiveof conductive portions or insulative portions, the surface to be bondedof the semiconductor element is silver-coated as with the base. Thesilver coating of the surface can be converted, as with the base, intosilver oxide by subjecting it to oxidizing treatment.

Mounting is performed while applying a pressure or an ultrasonicvibration to the semiconductor element or the base. The duration of theapplication of pressure or ultrasonic vibration depends on the conditionof the silver or silver oxide surface of the base, and may be suitablydetermined to sufficiently attain temporary bonding. For this mounting,the base may be heated in advance to 150 to 900° C., more preferably 150to 400° C., and still more preferably 150 to 320° C. The temporarybonding environment for silver-silver bonding is preferably an oxidizingenvironment containing oxygen or ozone, and more preferably air, whichis inexpensive. In the case of silver-silver oxide bonding or silveroxide-silver oxide bonding, an inert gas environment that does notcontain oxygen or ozone may be used, and a nitrogen environment, whichis inexpensive, is preferable.

A temperature of 150 to 900° C. is applied to the temporarily bondedbase and semiconductor element to increase the number of bonding pointsand to mutually diffuse silver, thereby allowing the bonding to bestrong and enabling permanent bonding to be attained. Metal diffusion isobtained as a function of temperature, and thus, the higher thetemperature, the faster the enhancement of bonding strength, but toavoid the oxidative degradation or the melting of plastic componentsused in the semiconductor device it is desirable to set the upper limitnear 320° C., below which general-purpose thermoplastic resins do notmelt. Note that, when a ceramics substrate or the like that is heatresistant is used for the base, the temperature can be increased tonearly 400° C. For the lower-limit temperature, 150° C. or a highertemperature is needed to obtain strong bonding within a practical timespan.

It is preferable to simultaneously perform the step of temporarilybonding and the step of permanently bonding. The semiconductor elementis mounted on the base while applying a pressure or a ultrasonicvibration, and then a temperature of 150 to 900° C., preferably 150 to400° C., and more preferably 150 to 320° C. is applied to increase thenumber of bonding points and to mutually diffuse silver, therebyenabling strong bonding to be created. In this manner, the number ofbonding points is greatly increased, and the enhancement of bondingstrength can thus be expected.

It is preferable that the step of permanently bonding is performed inair or in an oxygen environment. The environment in which heat isapplied to perform permanent bonding is preferably in air or in anoxygen environment. This is because an increase in the number of bondingpoints and, hence, an enhancement of the bonding strength can beexpected. In particular, the permanent bonding environment forsilver-silver bonding is preferably an oxidizing environment containingoxygen or ozone, and more preferably air, which is inexpensive. In thecase of silver-silver oxide bonding or silver oxide-silver oxidebonding, an inert gas environment may be selected, and a nitrogenenvironment, which is inexpensive, is preferable.

The present invention relates to a semiconductor device having a dieshear strength of 13 to 55 MPa in which silver or silver oxide providedon a surface of the base and silver or silver oxide provided on asurface of the semiconductor element are directly bonded. The die shearstrength is dependent on the heating temperature and the heating timeduring bonding, and the higher the temperature and the longer the time,the higher the strength, but the lower the temperature and the shorterthe time, the more advantageous it is when the production costs and theoxidative degradation of plastic components used in the semiconductordevice are taken into consideration. Therefore, the die shear strengthcan be controlled by selecting a heating temperature of 150 to 900° C.,preferably 150 to 400° C., and more preferably 150 to 320° C., andsuitably selecting a heating time. Practically, the semiconductor deviceneeds to withstand a ultrasonic shock during wire bonding and a thermalshock test performed thereon, and a die shear strength of 13 MPa orgreater is required, and the upper limit preferably is 55 MPa at whichthe die shear strength reaches saturation during permanent bondingperformed by heating at 320° C. To secure the reliability of thesemiconductor device and to lessen the deterioration of the initialproperties thereof, the die shear strength is more preferably 13 MPa to35 MPa.

A light emitting semiconductor element can be used for the semiconductorelement. Silver reflects more visible light than any other metal, andproviding a silver coating on a surface of the semiconductor elementalso serves to furnish the semiconductor element with a high-efficiencyreflector, creating a configuration highly suitable in a light emittingsemiconductor element. Moreover, providing a silver coating on a surfaceof the base allows the entire semiconductor device to have areflector-like structure, and it is thus possible to extract light evenmore efficiently. The translucent inorganic substrate used in the lightemitting semiconductor element, since it absorbs very little light, cancontribute to producing a light emitting semiconductor element that hasa high emission efficiency. In the light emitting semiconductor element,a light emitting layer that is a semiconductor layer is disposed on theupper surface of the translucent inorganic substrate, the light emittingsemiconductor element is arranged such that the light emitting layerbecomes the upper surface, and silver or silver oxide is provided on thelower surface on the side opposite the translucent inorganic substrate.It is thus possible to highly efficiently reflect the light emitted fromthe light emitting layer and to obtain a semiconductor device having alarge emission intensity.

In the semiconductor element, the semiconductor layer is disposed on thetranslucent inorganic substrate, and the translucent inorganic substrateis provided with first silver on the side opposite the semiconductorlayer and furnished with a buffering member that is bonded with thefirst silver. A buffering member on a surface of which is provided withsilver or silver oxide may be used. Formation of the first silverbetween the outermost silver or silver oxide and the translucentinorganic substrate can enhance the light reflectivity and thus enhancethe emission intensity of the semiconductor device. One or more layersof the buffering member are provided between the first silver and theoutermost silver or silver oxide. Various buffering members can beselected according to the material of the base and the material of thetranslucent inorganic substrate, and various inorganic materials andvarious organic materials can be used. Use of the buffering memberreduces or alleviates the stress generated between the translucentinorganic substrate and the base, and it is thus possible to enhancebonding reliability and prevent cracks in the translucent inorganicsubstrate.

Semiconductor Device Semiconductor Device of the First Embodiment

An example of the semiconductor device of the first embodiment isdescribed with reference to a drawing. FIG. 1 is a schematiccross-sectional drawing showing the semiconductor light emitting elementof the first embodiment when mounted. A description is given withreference to a light emitting semiconductor element that uses a lightemitting diode as a semiconductor element, but the present invention isapplicable also to transistors, ICs, LSIs, and the like other than lightemitting semiconductor elements.

In the semiconductor device, silver or silver oxide 520 provided on asurface of a base 500 and silver or silver oxide 140 provided on asurface of a light emitting semiconductor element 100 are directlybonded.

The light emitting semiconductor element 100 includes a translucentinorganic substrate 110, a semiconductor layer 120 that emits light, anelectrode 130 disposed on the semiconductor layer 120, first silver 150provided on the side opposite the side on which the semiconductor layer120 is disposed, a buffering member 160 bonded with the first silver,and the silver or silver oxide 140 provided on a surface of thebuffering member. In the semiconductor layer 120, an n-typesemiconductor layer 121 is stacked on the translucent inorganicsubstrate 110 and a p-type semiconductor layer 122 is stacked on then-type semiconductor layer 121. In the electrode 130, an n-typeelectrode 131 is disposed on the n-type semiconductor 121, and a p-typeelectrode 132 is disposed on the p-type semiconductor 122. The lightemitting semiconductor element 100 employs a flip chip structure thathas the n-type electrode 131 and the p-type electrode 132 on the sameside. One or more layers of the silver or silver oxide 140 may beprovided on a surface of the light emitting semiconductor element 100.Moreover, the thickness of the silver or silver oxide 140 provided on asurface of the light emitting semiconductor element 100 is notparticularly limited, but preferably is about 0.1 to 50 μm. It ispreferable to provide the first silver 150 to efficiently reflect thelight of the semiconductor layer 120. The thickness of the first silver150 can be suitably selected insofar as 85% or greater and preferably90% or greater of light can be reflected, e.g., 0.05 μm or greater.

The buffering member 160 can reduce or alleviate the bonding stressgenerated due to the difference between the mechanical properties of thetranslucent inorganic substrate 110 and the base 500. Various inorganicmaterials and organic materials can be used for the buffering member160, and multiple layers of such materials may be formed. A greatreduction in the stress that is generated during bonding can be expectedwith the use of an organic polymeric material for the buffering member160. Lest the exposed end portions of the buffering member 160 undergophotodegradation, an inorganic material is more preferable.

The silver or silver oxide 140 can be disposed below the bufferingmember 160, thereby allowing it to be bonded with the silver or silveroxide 520 provided on a surface of the base 500. For the silver andsilver oxide 140, use of silver oxide allows bonding to be accomplishedin an inert gas environment. Moreover, use of silver oxide can preventsulfuration and give storage stability to the light emittingsemiconductor element before being bonded. Silver oxide can be providedin such a manner that, first, silver is applied to the buffering member160 and then oxidized by oxygen plasma, UV irradiation, or a liketechnique, thereby giving silver oxide.

Note that, the silver or silver oxide 140 may be provided directly onthe translucent inorganic substrate 110. Furthermore, the silver orsilver oxide 140 is not necessarily provided in the form of a singlelayer and may be provided in the form of multiple layers composed of twoor more layers. Using the silver or silver oxide 140 in differentthicknesses or compositions, the bondability with the translucentinorganic substrate 110 can be enhanced.

In the base 500, the silver or silver oxide 520 is provided on a surfaceof a pedestal 510. The pedestal 510 may be conductive or insulative. Anexample of a conductive member used for the pedestal 510 includes a leadframe made of copper, iron, or a like material. If silver is used forthe pedestal 510, it is not necessary to provide the silver or silveroxide 520 and the pedestal 510 serves as the base 500.

On the other hand, examples of an insulative member used for thepedestal 510 include a glass epoxy board, a resin component such aspolyphthalamide or a liquid-crystal polymer, a ceramics component, and alike material. In the case where such an insulative member is used forthe pedestal 510, desired circuit wiring is installed on a glass epoxyboard and the silver or silver oxide 520 is provided on the circuitwiring.

For the silver and silver oxide 520 to be disposed on the pedestal 510,use of silver oxide allows bonding to be accomplished in an inert gasenvironment. Silver oxide can be provided in such a manner that, first,silver is applied to the pedestal 510 and then oxidized by oxygenplasma, UV irradiation, or a like technique, thereby giving silveroxide. Only a portion on which the light emitting semiconductor element100 is to be mounted may be oxidized. Silver oxide can be provided insuch a manner that, first, silver is applied to the buffering member 160and then oxidized by oxygen plasma, UV irradiation, or a like technique,thereby giving silver oxide.

The base 500 can take a variety of shapes such as a flat plate shape anda cup shape. For the ease of mounting the light emitting semiconductorelement 100, a base 500 in the shape of a flat plate is preferable. Toenhance the efficiency of extracting light from the light emittingsemiconductor element 100, the base 500 can take the shape of a cup. Inthe case where the base 500 is cup-shaped, part of the conductive wiringcan be exposed exterior of the base 500 as a terminal. Semiconductorlight emitting elements having the same function and semiconductorelements having different functions can be mounted on the base 500. Anelectronic element such as a resistive element and a capacitor may alsobe mounted on the base 500.

Wiring with a gold wire or the like is provided on the electrode 130disposed on the light emitting semiconductor element 100 to attain adesired electrical connection. The light emitting semiconductor element100 is encapsulated in an encapsulating member that contains afluorescent material, a filler, a light diffusing member, or the likethat absorbs the light emitted from the light emitting semiconductorelement 100 and converts the wavelength thereof into a differentwavelength, thereby giving a semiconductor device.

The die shear strength preferably is 13 to 55 MPa. Accordingly, thesemiconductor element and the base can be bonded firmly.

Method for Producing Semiconductor Device

The light emitting semiconductor element 100 is mounted on the base 500such that the silver or silver oxide 140 provided on a surface of thelight emitting semiconductor element 100 is brought into contact withthe silver or silver oxide 520 provided on a surface of the base 500. Nosolder, resin, or the like is present between the silver or silver oxide520 provided on a surface of the base 500 and the silver or silver oxide140 provided on a surface of the light emitting semiconductor element100. In the base 500, the pedestal 510 is provided with desired circuitwiring, and the silver or silver oxide 520 is provided on the outermostsurface of the circuit wiring. In connection with the positioning of thelight emitting semiconductor element 100, the circuit wiring may havevarious shapes, for example, circuit wiring having a shape identical tothe contour of the light emitting semiconductor element 100 can beformed, circuit wiring having a shape slightly smaller than butapproximately identical to the contour of the light emittingsemiconductor element 100 can be formed, or approximately square circuitwiring whose vertices extend to the four corners of the light emittingsemiconductor element 100 can be formed.

The light emitting semiconductor element 100 and the base 500 aretemporarily bonded by applying a pressure or a ultrasonic vibration tothe light emitting semiconductor element 100 or the base 500. A specificpressure or ultrasonic vibration may be applied during the mounting ofthe light emitting semiconductor element 100 on the base 500, or aspecific pressure or ultrasonic vibration may be applied by a separatemachine after the mounting of the light emitting semiconductor element100 on the base 500. Although the pressure applied when the lightemitting semiconductor element 100 and the base 500 are temporarilybonded is preferably 5 to 50 MPa and more preferably 10 to 20 MPa,pressures the light emitting semiconductor element 100 can withstand areacceptable. A temperature of 150 to 400° C. may be applied in advance tothe light emitting semiconductor element 100 and the base 500 whiletemporarily bonding. Although a longer duration is more preferable, thenecessary duration of the step of temporarily bonding is notparticularly limited and about 0.1 to 60 seconds is sufficient.

The light emitting semiconductor element 100 and the base 500 arepermanently bonded by applying a temperature of 150 to 900° C. to thelight emitting semiconductor element 100 and the base 500. The step oftemporarily bonding and the step of permanently bonding can be performedsimultaneously. The temperature applied to the light emittingsemiconductor element 100 and the base 500 preferably is 150° C. orgreater at which strong bonding can be attained. The temperature is notparticularly limited insofar as the light emitting semiconductor element100 can withstand the temperature, and it may be no greater than 900°C., which is lower than the melting point of silver, and no greater than400° C. or less is preferable. Moreover, a temperature of no greaterthan 320° C., which the light emitting semiconductor element 100 and apackaging can withstand, is particularly preferable. The step ofpermanently bonding can be performed also in air or in an oxygenenvironment. In the case where the silver 140 is used on a surface ofthe light emitting semiconductor element 100 and the silver 520 is usedon a surface of the base 500, permanent bonding is performed in anoxygen environment. In the case where the silver 140 is used on asurface of the light emitting semiconductor element 100 and the silveroxide 520 is used on a surface of the base 500 and in the case where thesilver oxide 140 is used on a surface of the light emittingsemiconductor element 100 and the silver or silver oxide layer 520 isused on a surface of the base 500, permanent bonding in both cases canbe performed in an inert gas environment such as a nitrogen environment,and it can be performed also in air or in an oxygen environment.Although a longer duration is more preferable, the necessary duration ofthe step of permanently bonding is also not particularly limited andabout 1 second to 24 hours is sufficient.

Note that, since the melting point of silver is 961° C., sintering isperformed in the present production process at a temperature of nogreater than 900° C., which is lower than the melting point of silver,and a temperature of 150 to 400° C. in particular is a very lowtemperature.

After the light emitting semiconductor element 100 is mounted on thebase 500, wires are connected and encapsulation in an encapsulatingmember is performed, thereby giving a semiconductor device.

Semiconductor Device of the Second Embodiment

An example of the semiconductor device of the second embodiment isdescribed with reference to a drawing. FIG. 2 is a schematiccross-sectional drawing showing the semiconductor light emitting elementof the second embodiment when mounted. The semiconductor device of thesecond embodiment has substantially the same configuration as thesemiconductor device of the first embodiment except for the lightemitting semiconductor element, and some descriptions may be omitted.

In the semiconductor device, silver or silver oxide 620 provided on asurface of a base 600 and silver or silver oxide 240 provided on asurface of a light emitting semiconductor element 200 are bonded.

The light emitting semiconductor element 200 includes a translucentinorganic substrate 210, a semiconductor layer 220 that emits light, ap-type electrode 232 disposed on the semiconductor layer 220, firstsilver 250 provided on the side opposite the side on which thesemiconductor layer 220 is disposed, a buffering member 260 bonded withthe first silver 250, and the silver or silver oxide 240 provided on asurface of the buffering member 260. The bottom part of the translucentinorganic substrate 210 serves as an n-type electrode. In thesemiconductor layer 220, an n-type semiconductor layer 221 is stacked onthe translucent inorganic substrate 210 and a p-type semiconductor layer222 is stacked on the n-type semiconductor layer 221. The light emittingsemiconductor element 200 includes the n-type electrode on thelower-surface side (bottom part of the translucent inorganic substrate210) and the p-type electrode 232.

In the base 600, the silver or silver oxide 620 is provided on aconductive or insulative pedestal 610.

In this manner, even for the light emitting semiconductor element 200,which has such a configuration that the electrodes are disposed on theupper and lower surfaces, the silver or silver oxide layer 620 providedon the base 600 can be firmly bonded under specific conditions with thesilver or silver oxide layer 240 by providing the silver or silver oxidelayer 240 on the outermost lower surface of the light emittingsemiconductor element 200 on which mounting is performed.

Semiconductor Device of the Third Embodiment

An example of the semiconductor device of the third embodiment isdescribed with reference to a drawing. FIG. 3 is a schematiccross-sectional drawing showing the semiconductor light emitting elementof the third embodiment when mounted. The semiconductor device of thesecond embodiment have substantially the same configuration as thesemiconductor device of the first embodiment except for the lightemitting semiconductor element, and some descriptions may be omitted.

In the semiconductor device, silver or silver oxide 720 provided on asurface of a base 700 and silver or silver oxide 340 provided on asurface of a light emitting semiconductor element 300 are bonded.

The light emitting semiconductor element 300 includes a translucentinorganic substrate 310, a semiconductor layer 320 that emits light, anelectrode 330 disposed on the semiconductor layer 320, and silver orsilver oxide 340 provided on the electrode 330. In the semiconductorlayer 320, an n-type semiconductor layer 321 is stacked on thetranslucent inorganic substrate 310 and a p-type semiconductor layer 322is stacked on the n-type semiconductor layer 321. In the electrode 330,an n-type electrode 331 is disposed on the n-type semiconductor layer321, and a p-type electrode 332 is disposed on the p-type semiconductorlayer 322. The light emitting semiconductor element 300 employs a flipchip structure that has the n-type electrode 331 and the p-typeelectrode 332 on the same side and is mounted facedown. The n-typeelectrode 331 and the p-type electrode 332 are both provided on theirsurfaces with silver or silver oxide 340. It is preferable that thesilver or silver oxide 340 covers the entire surfaces of the n-typeelectrode 331 and the p-type electrode 332, but the silver or silveroxide layer 340 may be applied only to the portion that is brought intocontact with the base 700. One or more layers of the silver or silveroxide 340 may be provided on a surface of the light emittingsemiconductor element 300. Moreover, the thickness of the silver orsilver oxide 340 provided on a surface of the light emittingsemiconductor element 300 is not particularly limited, and preferably isabout 0.1 to 50 μm. In order to mount the light emitting semiconductorelement 300 facedown, it is preferable to adjust the heights of then-type electrode 331 and the p-type electrode 332 such that thetranslucent inorganic substrate 310 is disposed approximately parallelto the base.

In the base 700, a desired circuit pattern is provided on an insulativemount 710, and the silver or silver oxide 720 is provided on the circuitpattern.

In this manner, even for the light emitting semiconductor element 300,which has such a configuration that the n-type electrode 331 and thep-type electrode 332 are disposed on the same side and is mountedfacedown, the silver or silver oxide layer 720 provided on the base 700can be firmly bonded under specific conditions with the silver or silveroxide layer 340 by providing the silver or silver oxide layer 340 on then-type electrode 331 and the p-type electrode 332. In particular, sinceno solder bumps are used, bonding can be achieved without creating ashort circuit even when the distance between the n-type electrode 331and the p-type electrode 332 is small.

The method for producing the semiconductor device of the thirdembodiment is also nearly the same as the method for producing thesemiconductor device of the first embodiment except that no step of wireconnection is needed after the bonding of the light emittingsemiconductor element 300 and the base 700.

Semiconductor Element

For the semiconductor element, in addition to light emittingsemiconductor elements such as light emitting diodes and laser diodes,transistors, ICs, LSIs, Zener diodes, capacitors, light receivingelements, and the like can be used.

In the light emitting semiconductor element, a semiconductor layer isstacked on an inorganic substrate. The inorganic substrate preferably istranslucent. Sapphire, GaP, GaN, ITO, ZnO, inorganic glass, ceramics,and the like can be used for the translucent inorganic substrate, and asemiconductor such as GaAlN, ZnS, ZnSe, SiC, GaP, GaAlAs, AlN, InN,AlInGaP, InGaN, GaN, or AlInGaN processed into a light emitting layer isused for the semiconductor layer. The structure of the semiconductor maybe a homostructure, a heterostructure, or a double heterostructure, thathas an MIS junction, a PIN junction, or a PN junction. Various emissionwavelengths, from ultraviolet light to infrared light, can be selectedaccording to the material of the semiconductor layer and the compositionof the mixed crystals thereof. The light emitting layer may have asingle quantum well structure or a multiple quantum well structure inthe form of a thin film that exhibits a quantum effect.

If outdoor use or use in a like environment is considered, a galliumnitride compound semiconductor preferably is used for a semiconductorlayer that can form a high-intensity light emitting semiconductorelement, and a gallium/aluminium/arsenic semiconductor layer and analuminium/indium/gallium/phosphorus semiconductor layer preferably areused to create red, and various semiconductors can be used depending onthe application.

In the case where a gallium nitride compound semiconductor is used forthe semiconductor layer, materials such as sapphire, spinel, SiC, Si,ZnO, and GaN are used for the translucent inorganic substrate. It ispreferable to use sapphire for the translucent inorganic substrate toproduce highly crystalline gallium nitride that can easily be massproduced. In the case where the light emitting semiconductor element isused facedown, the translucent inorganic substrate is required to havehigh translucency.

Although the electrode preferably is of a material that does not blocklight, a light blocking material can also be used. In the case where thelight emitting semiconductor element is provided with an n-typeelectrode and a p-type electrode on the same side, it is preferable thatthe p-type electrode is provided to occupy a large area of thesemiconductor layer.

In the case where the light emitting semiconductor element is providedwith an n-type electrode and a p-type electrode on the upper and lowersurfaces, it is preferable that the electrode on the side that isbrought into contact with the base is provided so as to occupy a largearea, and it is particularly preferable that the electrode is providedso as to occupy nearly the entire lower surface. The electrode on theside that is brought into contact with the base preferably is coveredwith silver or silver oxide.

The translucent p-type electrode may be formed as a thin film having athickness of 150 μm or less. Moreover, non-metal materials such as ITOand ZnO can also be used for the p-type electrode. Here, in place of thetranslucent p-type electrode, an electrode that has a plurality ofopenings for light extraction, such as a mesh electrode, may be used.

In addition to a linear shape, the electrode may take, for example, acurved, whisker, comb, lattice, branch, hook, or network shape. Thelight blocking effect is increased proportional to the total area of thep-type electrode, it is thus preferable to design the line width andlength of an extended conductive part such that the light emissionenhancing effect is not overwhelmed by the light blocking effect. Metalssuch as Au and Au—Sn as well as non-metal materials such as ITO and ZnOcan be used for the p-type electrode. In place of the translucent p-typeelectrode, an electrode that has a plurality of openings for lightextraction, such as a mesh electrode, may be used. The size of the lightemitting semiconductor element may be suitably selected.

The buffering member of the light emitting semiconductor elementpreferably contains at least one inorganic material, other than silverand silver oxide, selected from the group consisting of gold, copper,aluminium, tin, cobalt, iron, indium, tungsten and like metals as wellas alloys thereof, silica, alumina, zirconium oxide, titanium oxide, andlike oxides; and aluminium nitride, zirconium nitride, titanium nitride,and like nitrides. The buffering member of the light emittingsemiconductor element preferably contains at least one organic materialselected from the group consisting of an epoxy resin, a silicone resin,a modified silicone resin, a polyimide resin, and like insulativeresins; and conductive resins that are produced by filling suchinsulative resins with large amounts of metal powder.

If silver oxide is to be provided on the outermost surface of thesemiconductor element, silver is applied first and then oxidized byoxygen plasma, UV irradiation, or a like technique, thereby givingsilver oxide. The formation of silver oxide allows bonding to beachieved in an inert gas environment. The sulfuration of silver can beprevented.

Base

In the base, silver or silver oxide is provided on a surface of thepedestal. A ceramic substrate containing aluminium oxide, aluminiumnitride, zirconium oxide, zirconium nitride, titanium oxide, titaniumnitride, or a mixture of these, a metal substrate containing Cu, Fe, Ni,Cr, Al, Ag, Au, Ti, or an alloy of these, a lead frame, a glass epoxyboard, a BT resin substrate, a glass substrate, a resin substrate,paper, and the like can be used for the base. An example of the leadframe is a metal frame formed from copper, iron, nickel, chromium,aluminium, silver, gold, titanium, or an alloy of these, and a metalframe formed from copper, iron, or an alloy of these is preferable. Morepreferably, the lead frame is of a copper alloy in the case of asemiconductor device that needs to have heat releasability, and of aniron alloy in the case of a semiconductor device in which thesemiconductor element needs to be reliably bonded. In the case wheresilver or silver oxide is used in the portion corresponding to thepedestal of the base, it is not necessary to further provide silver orsilver oxide.

The surface of the wiring board or the lead frame may be coated withsilver, silver oxide, silver alloy, silver alloy oxide, Pt, Pt alloy,Sn, Sn alloy, gold, gold alloy, Cu, Cu alloy, Rh, Rh alloy, or the like,and the outermost surface of the portion on which the semiconductorelement is to be mounted is coated with silver or silver oxide. Coatingwith such materials can be performed by plating, vapor deposition,sputtering, printing, applying, or a like technique.

A resin package may be used for the base. A package in which a lead ismolded integrally and a package in which circuit wiring is created byplating or a like technique after package molding may be usable. Thepackage can take a variety of shapes such as a cup shape and a flatplate shape. An electrically insulative resin that has excellent lightresistance and heat resistance is suitably used for the resin that formsthe package and, for example, a thermoplastic resin such aspolyphthalamide, a thermosetting resin such as an epoxy resin, glassepoxy, and ceramics can be used. Moreover, to efficiently reflect thelight emitted from the light emitting semiconductor element, a whitepigment such as titanium oxide can be added to such resins. Usablemethods of package molding include insert molding in which a lead isplaced in advance in a metal mold, injection molding, extrusion molding,transfer molding, and the like.

Encapsulating Member

An encapsulating member is used to protect the semiconductor devicemounted on the base from external forces, dust, etc. Also, theencapsulating member can let the light emitted from the light emittingsemiconductor element efficiently pass through outwardly. Examples ofresins used for the encapsulating member include an epoxy resin, aphenolic resin, an acrylic resin, a polyimide resin, a silicone resin, aurethane resin, a thermoplastic resin, and the like. In particular, asilicone resin is preferable since a long-lasting semiconductor devicethat has excellent heat resistance and light resistance can be produced.For an airtight cover or a non-airtight cover, inorganic glass, apolyacrylic resin, a polycarbonate resin, a polyolefin resin, apolynorbornene resin, and the like can be mentioned. In particular,inorganic glass is preferable since a long-lasting semiconductor devicethat has excellent heat resistance and light resistance can be produced.

Others

The encapsulating member may contain a fluorescent material, a filler, alight diffusing member, and the like. The fluorescent material may beany material that absorbs the light emitted from the light emittingsemiconductor element and emits a fluorescence having a wavelengthdifferent from that of the light, and preferably is at least one memberselected from a nitride phosphor or an oxynitride phosphor that isactivated primarily by a lanthanoid element such as Eu or Ce; analkaline earth halogen apatite phosphor, a halogenated alkaline earthmetal borate phosphor, an alkaline earth metal aluminate phosphor, analkaline earth silicate phosphor, an alkaline earth sulfide phosphor, analkaline earth thiogallate phosphor, an alkaline earth silicon nitridephosphor, and a germanate phosphor that are activated primarily by alanthanoid element such as Eu or a transition metal element such as Mn;a rare earth aluminate phosphor and a rare earth silicate phosphor thatare activated primarily by a lanthanoid element such as Ce; and organicand inorganic complexes that are activated primarily by a lanthanoidelement such as Eu; and the like. More preferably,(Y,Gd)₃(Al,Ga)₅O₁₂:Ce, (Ca,Sr,Ba)₂SiO₄:Eu, (Ca,Sr)₂Si₅N₈:Eu,CaAlSiN₃:Eu, and the like are used.

For the filler, alumina, silica, tin oxide, zinc oxide, titanium oxide,magnesium oxide, silicon nitride, boron nitride, aluminium nitride,potassium titanate, mica, calcium silicate, magnesium sulfate, bariumsulfate, aluminium borate, glass flake, and glass fiber can be used. Inaddition, silicone rubber particles and silicone elastomer particles canbe used for stress relaxation. The light transmittance is greatlyinfluenced by the diameter of the filler particles, and the averageparticle diameter preferably is 5 μm or greater, but nanoparticles canalso be used. It is thus possible to greatly enhance the translucencyand light dispersibility of the encapsulating member.

For the light diffusing member, alumina, silica, tin oxide, zinc oxide,titanium oxide, magnesium oxide, silicon nitride, boron nitride,aluminium nitride, potassium titanate, mica, calcium silicate, magnesiumsulfate, barium sulfate, aluminium borate, glass flake, and glass fibercan be used. In addition, particles of thermosetting resins such as anepoxy resin, a silicone resin, a benzoguanine resin, and a melamineresin can be used. The light diffusibility is greatly influenced by thediameter of the filler particles, and the average particle diameterpreferably is in a range of 0.1 to 5 μm. It is thereby possible toattain light diffusion with a smaller amount of light diffusing member.

The semiconductor element can be coated with the fluorescent material,the filler, and the light diffusing member also by printing, potting,electrodeposition, and stamping. The encapsulating member can be appliedto the upper surface thereof. This makes optical design easy in the casewhere the encapsulating member has a lens shape and enables ahigh-quality semiconductor device to be obtained.

EXAMPLES

Below, the semiconductor device and the production method therefor ofthe present invention will be described by way of examples. Thesemiconductor devices of Example 1 to 19 are encompassed within thesemiconductor device of the first embodiment, and some descriptions maytherefore be omitted.

Example 1

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about150° C. for about 5 hours. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 2

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about320° C. for about 15 minutes. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 3

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped alumina ceramics substratewas formed as a pedestal 510, and silver 520 with which the surface ofan underlying metal disposed on the alumina ceramics substrate wassilver-plated was used. The alumina ceramics substrate was formed bystacking alumina ceramics in the shape of a cup, providing an underlyingmetal thereon, sintering the alumina ceramics, and silver-plating thesurface of the underlying metal of the sintered alumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about150° C. for about 10 hours. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 4

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped alumina ceramics substratewas formed as a pedestal 510, and silver 520 with which the surface ofan underlying metal disposed on the alumina ceramics substrate wassilver-plated was used. The alumina ceramics substrate was formed bystacking alumina ceramics in the shape of a cup, providing an underlyingmetal thereon, sintering the alumina ceramics, and silver-plating thesurface of the metal strip of the sintered alumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about320° C. for about 1 hour. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 5

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped package was formed asa pedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, a pressure of about 15 MPa was applied in the directionfrom the upper surface of the light emitting semiconductor element 100toward the base 500 and maintained for about 10 seconds. Furthermore,permanent bonding was performed as follows: the base 500 temporarilybonded with the light emitting semiconductor element 100 was heated in anitrogen stream at about 150° C. for about 7 hours. It was thus possibleto directly bond the light emitting semiconductor element 100 and thebase 500.

Example 6

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped package was formed asa pedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, a pressure of about 15 MPa was applied in the directionfrom the upper surface of the light emitting semiconductor element 100toward the base 500 and maintained for about 10 seconds. Furthermore,permanent bonding was performed as follows: the base 500 temporarilybonded with the light emitting semiconductor element 100 was heated in anitrogen stream at about 320° C. for about 1 hour. It was thus possibleto directly bond the light emitting semiconductor element 100 and thebase 500.

Example 7

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped alumina ceramicssubstrate was formed as a pedestal 510, and silver 520 with which thesurface of an underlying metal disposed on the alumina ceramicssubstrate was silver-plated was used. The alumina ceramics substrate wasformed by stacking alumina ceramics in the shape of a cup, providing anunderlying metal thereon, sintering the alumina ceramics, andsilver-plating the surface of the underlying metal of the sinteredalumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, a pressure of about 15 MPa was applied in the directionfrom the upper surface of the light emitting semiconductor element 100toward the base 500 and maintained for about 10 seconds. Furthermore,permanent bonding was performed as follows: the base 500 temporarilybonded with the light emitting semiconductor element 100 was heated in anitrogen stream at about 150° C. for about 15 hours. It was thuspossible to directly bond the light emitting semiconductor element 100and the base 500.

Example 8

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped alumina ceramicssubstrate was formed as a pedestal 510, and silver 520 with which thesurface of an underlying metal disposed on the alumina ceramicssubstrate was silver-plated was used. The alumina ceramics substrate wasformed by stacking alumina ceramics in the shape of a cup, providing anunderlying metal thereon, sintering the alumina ceramics, andsilver-plating the surface of the underlying metal of the sinteredalumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, a pressure of about 15 MPa was applied in the directionfrom the upper surface of the light emitting semiconductor element 100toward the base 500 and maintained for about 10 seconds. Furthermore,permanent bonding was performed as follows: the base 500 temporarilybonded with the light emitting semiconductor element 100 was heated in anitrogen stream at about 320° C. for about 3 hours. It was thus possibleto directly bond the light emitting semiconductor element 100 and thebase 500.

Example 9

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, ultrasonic waves of about 60 kHz were applied in the direction fromthe upper surface of the light emitting semiconductor element 100 towardthe base 500 and maintained for about 1 second. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about150° C. for about 3 hours. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 10

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair; ultrasonic waves of about 60 kHz were applied in the direction fromthe upper surface of the light emitting semiconductor element 100 towardthe base 500 and maintained for about 1 second. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about320° C. for about 15 minutes. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 11

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped alumina ceramics substratewas formed as a pedestal 510, and silver 520 with which the surface ofan underlying metal disposed on the alumina ceramics substrate wassilver-plated was used. The alumina ceramics substrate was formed bystacking alumina ceramics in the shape of a cup, providing an underlyingmetal thereon, sintering the alumina ceramics, and silver-plating thesurface of the underlying metal of the sintered alumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, ultrasonic waves of about 60 kHz were applied in the direction fromthe upper surface of the light emitting semiconductor element 100 towardthe base 500 and maintained for about 1 second. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about150° C. for about 5 hours. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 12

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped alumina ceramics substratewas formed as a pedestal 510, and silver 520 with which the surface ofan underlying metal disposed on the alumina ceramics substrate wassilver-plated was used. The alumina ceramics substrate was formed bystacking alumina ceramics in the shape of a cup, providing an underlyingmetal thereon, sintering the alumina ceramics, and silver-plating thesurface of the underlying metal of the sintered alumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, ultrasonic waves of about 60 kHz were applied in the direction fromthe upper surface of the light emitting semiconductor element 100 towardthe base 500 and maintained for about 1 second. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about320° C. for about 30 minutes. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Example 13

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped package was formed asa pedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, ultrasonic waves of about 60 kHz were applied in thedirection from the upper surface of the light emitting semiconductorelement 100 toward the base 500 and maintained for about 1 second.Furthermore, permanent bonding was performed as follows: the base 500temporarily bonded with the light emitting semiconductor element 100 washeated in a nitrogen stream at about 150° C. for about 4 hours. It wasthus possible to directly bond the light emitting semiconductor element100 and the base 500.

Example 14

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped package was formed asa pedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, ultrasonic waves of about 60 kHz were applied in thedirection from the upper surface of the light emitting semiconductorelement 100 toward the base 500 and maintained for about 1 second.Furthermore, permanent bonding was performed as follows: the base 500temporarily bonded with the light emitting semiconductor element 100 washeated in a nitrogen stream at about 320° C. for about 30 minutes. Itwas thus possible to directly bond the light emitting semiconductorelement 100 and the base 500.

Example 15

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped alumina ceramicssubstrate was formed as a pedestal 510, and silver 520 with which thesurface of an underlying metal disposed on the alumina ceramicssubstrate was silver-plated was used. The alumina ceramics substrate wasformed by stacking alumina ceramics in the shape of a cup, providing anunderlying metal thereon, sintering the alumina ceramics, andsilver-plating the surface of the underlying metal of the sinteredalumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, ultrasonic waves of about 60 kHz were applied in thedirection from the upper surface of the light emitting semiconductorelement 100 toward the base 500 and maintained for about 1 second.Furthermore, permanent bonding was performed as follows: the base 500temporarily bonded with the light emitting semiconductor element 100 washeated in a nitrogen stream at about 150° C. for about 10 hours. It wasthus possible to directly bond the light emitting semiconductor element100 and the base 500.

Example 16

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silveroxide 140, was used. For a base 500, a cup-shaped alumina ceramicssubstrate was formed as a pedestal 510, and silver 520 with which thesurface of an underlying metal disposed on the alumina ceramicssubstrate was silver-plated was used. The alumina ceramics substrate wasformed by stacking alumina ceramics in the shape of a cup, providing anunderlying metal thereon, sintering the alumina ceramics, andsilver-plating the surface of the underlying metal of the sinteredalumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver oxide 140 thereof was directly in contact with the silver 520 ofthe base 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. in anitrogen stream, ultrasonic waves of about 60 kHz were applied in thedirection from the upper surface of the light emitting semiconductorelement 100 toward the base 500 and maintained for about 1 second.Furthermore, permanent bonding was performed as follows: the base 500temporarily bonded with the light emitting semiconductor element 100 washeated in a nitrogen stream at about 320° C. for about 2 hours. It wasthus possible to directly bond the light emitting semiconductor element100 and the base 500.

Reference Example 1

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about140° C. for about 24 hours. It was thus possible to directly bond thelight emitting semiconductor element 100 and the base 500.

Results of Measurement

The die shear strength of the semiconductor devices of Examples 1 to 16and Reference Example 1 was measured. For the measurement of die shearstrength, a shearing force was applied at room temperature in adirection stripping the light emitting semiconductor element 100 off thebase 500, and the intensity of the force when the light emittingsemiconductor element 100 was stripped off was determined. Moreover, thelight reflectivity for light having a wavelength of 470 nm of thesemiconductor devices of Examples 1, 2, 5, 6, 9, 10, 13, and 14 thatused a package was measured. The results of the die shear strength (gf)and light reflectivity (%) measurement are presented in Table 1.

TABLE 1 Example Die shear strength (gf) Light reflectivity (%) Example 1512.7 87 Example 2 501.0 85 Example 3 503.4 — Example 4 530.2 — Example5 510.3 89 Example 6 522.3 87 Example 7 505.9 — Example 8 516.7 —Example 9 510.4 88 Example 10 520.6 85 Example 11 500.3 — Example 12544.1 — Example 13 520.5 90 Example 14 514.8 88 Example 15 538.2 —Example 16 565.3 — Ref. Ex. 1 238.2 84

According to the results of the measurement, it was found that thehigher the temperature of the permanent bonding, the shorter the timetaken to attain the desired die shear strength. It was found that apractical die shear strength can be obtained by selecting a temperatureof 150° C. or greater and a suitable heating time. Although thetemperature of 320° C. was employed in view of the heat resistance ofthe package and the light emitting semiconductor element, highertemperatures can be employed when a package and a semiconductor elementof greater heat resistance are used. It was found that bonding can beaccomplished in a nitrogen stream by providing silver oxide on the lightemitting semiconductor element side. Although not presented as anexample, bonding can be similarly accomplished in a nitrogen stream in asemiconductor device in which silver oxide is provided on the base side.

The light reflectivity obtained in the examples was all 85% or greaterand very high. Moreover, it was possible to alleviate the reduction inlight reflectivity resulting from the discoloration of the epoxy resinused in the package. Use of a ceramics component for the base canprovide a semiconductor device that does not undergo thermaldegradation.

On the other hand, although bonding was accomplished at a heatingtemperature of 140° C. in Reference Example 1, the die shear strengthwas not sufficient.

Note that, because of the difference between the thermal conductivitiesof the ceramics component used for the base and the epoxy resin as wellas other reasons, the time taken to achieve the desired die shearstrength may sometimes be different even when the same temperature wasapplied.

Examples 17 to 19

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about320° C. for 3 different durations, i.e., about 1 hour (Example 17),about 2 hours (Example 18), and about 3 hours (Example 19). It was thuspossible to directly bond the light emitting semiconductor element 100and the base 500.

Results of Measurement

The die shear strength of the semiconductor devices of Examples 17 to 19was measured. For the measurement of die shear strength, a shearingforce was applied at room temperature in a direction stripping the lightemitting semiconductor element 100 off the base 500, and the intensityof the force when the light emitting semiconductor element 100 wasstripped off was determined. The results of the die shear strength (gf)measurement are presented in Table 2.

TABLE 2 Example Die shear strength (gf) Example 17 1824.3 Example 181907.6 Example 19 1978.4

According to these results, it was found that the longer the heatingtime, the greater the die shear strength. Moreover, it was demonstratedthat permanent bonding performed at 320° C. can give a die shearstrength of about 2000 gf (55 MPa).

Initial Properties Comparative Example 1

Bonding was performed using the same components as in Example 1 exceptthat a clear colorless insulative epoxy resin was used as a die bondingcomponent in Comparative Example 1. Curing was performed at 170° C. for1 hour. The die shear strength attained in Comparative Example 1 wasabout 900 gf.

Comparative Example 2

Bonding was performed using the same components as in Example 1 exceptthat a silver paste containing 80 wt % of a flaky silver filler and 20wt % of an epoxy resin was used in Comparative Example 2. Curing wasperformed at 150° C. for 1 hour. The die shear strength attained inComparative Example 2 was about 1500 gf.

Results of Measurement

In connection with Example 1, Comparative Example 1, and ComparativeExample 2, the electrode of the light emitting semiconductor element andthe electrode of the base were gold-wired and encapsulated in a siliconeresin, thereby giving a semiconductor device. The emission intensity ofeach semiconductor device as-is was measured. The emission intensity ispresented as a value relative to the intensity obtained in Example 1being 100%. Table 3 shows the results of measurement.

TABLE 3 Relative intensity of Bonding emission (%) Ex. 1 Direct Agbonding 100 Comp. Ex. 1 Bonding with 95 insulative epoxy resin Comp. Ex.2 Bonding with flaky silver 85 filler-containing epoxy resin

As can be understood from the results of measurement, a semiconductordevice that had the highest emission intensity was obtained fromExample 1. It can be presumed that the emission intensity was lower inComparative Example 1 because the insulative epoxy resin formed a filletand, in addition, the color of the epoxy resin turned slightly yellowwhen cured. Similarly, it can be presumed that the intensity of emissionwas much lower in Comparative Example 2 because the flaky silverfiller-containing epoxy resin formed a fillet and, in addition, thecolor of the epoxy resin turned slightly yellow when cured and,simultaneously, light scattering due to the flaky silver filleroccurred.

Power-On Test

An electric current was applied to the semiconductor devices of Example1, Comparative Example 1, and Comparative Example 2 as-is (testconditions: 25° C. and 50 mA) for 500 hours, 1000 hours, and 2000 hours,and the emission intensity was then measured. Table 4 shows theintensity relative to the initial intensity

TABLE 4 After 500 After 1000 After 2000 Bonding hours hours hours Ex. 1Direct Ag bonding 99% 99% 99% Comp. Ex. 1 Bonding with 95% 80% 60%insulative epoxy resin Comp. Ex. 2 Bonding with flaky 93% 75% 60% silverfiller-containing epoxy resin

It was demonstrated that the semiconductor device obtained in Example 1can maintain high emission intensity even after 2000 hours. On the otherhand, it was demonstrated that the semiconductor devices obtained inComparative Examples 1 and 2 exhibited severely impaired intensity after2000 hours.

Furthermore, it was demonstrated that no discoloration can be observedin the periphery of the light emitting semiconductor element of Example1 even after 2000 hours. On the other hand, it was demonstrated that thecolor of the clear colorless insulative epoxy resin of ComparativeExample 1 disposed for bonding between the light emitting semiconductorelement and the base as well as the fillet portions was dark reddishbrown after 2000 hours. Moreover, it was demonstrated that the color ofthe silver paste containing 80 wt % of a flaky silver filler and 20 wt %of an epoxy resin of Comparative Example 2 disposed for bonding betweenthe light emitting semiconductor element and the base as well as thefillet portions was dark reddish brown after 2000 hours.

Example 20

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped package was formed as apedestal 510, and silver 520 with which the surface of a lead frameexposed on the outside of the package was silver-plated was used. Thepackage was formed by arranging a lead frame that used copper as aprimary component on an epoxy resin in which a white pigment wasdispersed and subjecting it to insert molding.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, bonding was performed asfollows: the lead frame was preheated to about 250° C. in air, apressure of about 15 MPa was applied in the direction from the uppersurface of the light emitting semiconductor element 100 toward the base500, and heating was performed at about 250° C. for about 1 hour. It wasthus possible to directly bond the light emitting semiconductor element100 and the base 500. Carrying out temporary bonding and permanentbonding in one step can simplify the process.

Example 21

For a light emitting semiconductor element 100, a translucent inorganicsapphire substrate 110 having the dimensions of 600 μm×600 μm×100 μm(thickness), on the upper surface of which was stacked a semiconductorInGaN layer 120 and the lower layer of which was metallized with silver140, was used. For a base 500, a cup-shaped alumina ceramics substratewas formed as a pedestal 510, and silver 520 with which the surface ofan underlying metal disposed on the alumina ceramics substrate wassilver-plated was used. The alumina ceramics substrate was formed bystacking alumina ceramics in the shape of a cup, providing an underlyingmetal thereon, sintering the alumina ceramics, and silver-plating thesurface of the underlying metal of the sintered alumina ceramics.

The light emitting semiconductor element 100 was mounted such that thesilver 140 thereof was directly in contact with the silver 520 of thebase 500. In connection with this mounting, temporary bonding wasperformed as follows: the lead frame was preheated to about 250° C. inair, a pressure of about 15 MPa was applied in the direction from theupper surface of the light emitting semiconductor element 100 toward thebase 500 and maintained for about 10 seconds. Furthermore, permanentbonding was performed as follows: the base 500 temporarily bonded withthe light emitting semiconductor element 100 was heated in air at about380° C. for about 5 minutes. It was thus possible to directly bond thesemiconductor light emitting element 100 and the base 500 in a shorttime.

Example 22

For a semiconductor device 100, a Zener diode was used in place of alight emitting semiconductor element. For the semiconductor element 100,an Si substrate 110 having the dimensions of 300 μm×300 μm×200 μm(thickness), on the upper surface of which was formed a semiconductorlayer 120 and the lower layer of which was metallized with silver 140,was used. For a base 500, a cup-shaped package was formed as a pedestal510, and silver 520 with which the surface of a lead frame exposed onthe outside of the package was silver-plated was used. The package wasformed by arranging a lead frame that used copper as a primary componenton an epoxy resin in which a white pigment was dispersed and subjectingit to insert molding.

The semiconductor element 100 was mounted such that the silver 140thereof was directly in contact with the silver 520 of the base 500. Inconnection with this mounting, temporary bonding was performed asfollows: the lead frame was preheated to about 250° C. in air, apressure of about 15 MPa was applied in the direction from the uppersurface of the semiconductor element 100 toward the base 500 andmaintained for about 10 seconds. Furthermore, permanent bonding wasperformed as follows: the base 500 temporarily bonded with thesemiconductor element 100 was heated in air at about 150° C. for about 5hours. It was thus possible to directly bond the semiconductor element100 and the base 500 in a short time. Use of a light emitting diode anda Zener diode in one package allows them to be permanently bondedsimultaneously after accomplishing the temporary bonding of the lightemitting diode and the temporary bonding of the Zener diode, and it wasthus possible to simplify the production process.

Example 23

For a semiconductor device 100, an IC chip was used in place of a lightemitting semiconductor element. For the semiconductor element 100, aninorganic Si substrate 110 having the dimensions of 300 μm×300 μm×200 μm(thickness), on the upper surface of which was formed a semiconductorlayer 120 and the lower layer of which was metallized with silver 140,was used. For a base 500, a cup-shaped package was formed as a pedestal510, and silver 520 with which the surface of a lead frame exposed onthe outside of the package was silver-plated was used. The package wasformed by arranging a lead frame that used copper as a primary componenton an epoxy resin in which a white pigment was dispersed and subjectingit to insert molding.

The semiconductor element 100 was mounted such that the silver 140thereof was directly in contact with the silver 520 of the base 500. Inconnection with this mounting, temporary bonding was performed asfollows: the lead frame was preheated to about 250° C. in air, apressure of about 15 MPa was applied in the direction from the uppersurface of the semiconductor element 100 toward the base 500 andmaintained for about 10 seconds. Furthermore, permanent bonding wasperformed as follows: the base 500 temporarily bonded with the lightemitting semiconductor element 100 was heated in air at about 380° C.for about 5 minutes. It was thus possible to directly bond thesemiconductor element 100 and the base 500 in a short time.

The method for producing a semiconductor device of the present inventionis applicable to, for example, the connection of component electrodes,die attaching, fine-pitch bumping, flat panels, solar wiring and likeproduction applications, and wafer connection and like applications aswell as to the production of electronic parts produced by assemblingsuch components. Moreover, the method for producing a semiconductordevice of the present invention is applicable when, for example,semiconductor devices that use light emitting semiconductor elementssuch as LEDs and LDs are produced.

DESCRIPTION OF REFERENCE NUMERALS

-   100, 200, 300: Light emitting semiconductor element-   110, 210, 310: Translucent inorganic substrate-   120, 220, 320: Semiconductor layer-   121, 221, 321: N-type semiconductor-   122, 222, 322: P-type semiconductor-   130, 330: Electrode-   131, 331: N-type electrode-   132, 232, 332: P-type electrode-   140, 240, 340: Silver or silver oxide-   150, 250: First silver-   160, 260: Buffering member-   500, 600, 700: Base-   510, 610, 710: Pedestal-   520, 620, 720: Silver or silver oxide

The invention may be embodied in other forms without departing from thespirit or essential characteristics thereof. The embodiments disclosedin this application are to be considered in all respects as illustrativeand not limiting. The scope of the invention is indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are intended to be embraced therein.

What is claimed is:
 1. A semiconductor device having a die shearstrength of 13 to 55 MPa in which silver or silver oxide provided on asurface of a base and silver or silver oxide provided on a surface of asemiconductor element are directly bonded.
 2. The semiconductor deviceaccording to claim 1, wherein the semiconductor element is a lightemitting semiconductor element.
 3. The semiconductor device according toclaim 1, wherein a semiconductor layer is disposed on a translucentinorganic substrate, the translucent inorganic substrate is providedwith first silver on the side opposite the semiconductor layer andfurnished with a buffering member that is bonded with the first silver,and silver or silver oxide is provided on a surface of the bufferingmember.
 4. The semiconductor device according to claim 2, wherein thethickness of the silver or silver oxide provided on a surface of thelight emitting semiconductor element is 0.1 to 50 μm.
 5. Thesemiconductor device according to claim 2, wherein two or more layers ofthe silver or silver oxide is provided on a surface of the lightemitting semiconductor element.
 6. The semiconductor device according toclaim 3, wherein the thickness of the first silver is 0.05 μm orgreater.
 7. The semiconductor device according to claim 3, wherein thebuffering member is made by an inorganic or organic material.
 8. Thesemiconductor device according to claim 3, wherein the buffering membercontains at least one selected from the group consisting of gold,copper, aluminium, tin, cobalt, iron, and indium, tungsten as well asalloys thereof; silica, alumina, zirconium oxide, and titanium oxide;and aluminium nitride, zirconium nitride, and titanium nitride.
 9. Thesemiconductor device according to claim 3, wherein the buffering membercontains at least one selected from the group consisting of insulativeresin of an epoxy resin, a silicone resin, a modified silicone resin,and a polyimide resin; and conductive resins that are produced byfilling insulative resins with metal powder.
 10. The semiconductordevice according to claim 3, wherein the buffering member is made bymultiple layers.
 11. The semiconductor device according to claim 1,wherein the base is at least one selected from the group consisting of ametal substrate, a lead frame, a glass epoxy board, a BT resinsubstrate, a glass substrate, a resin substrate and paper.
 12. Thesemiconductor device according to claim 1, wherein the base is a resinpackage.
 13. The semiconductor device according to claim 1, wherein theshape of the base is a flat plate shape or a cup shape.
 14. Thesemiconductor device according to claim 1, wherein the semiconductorelement is covered by an encapsulating member.
 15. The semiconductordevice according to claim 14, wherein the encapsulating member containsa fluorescent material, a filler, or a light diffusing member.